System and methods for thermal isolation of components used

ABSTRACT

An isolator system for preventing the conduction of thermal energy between the metal components of a wall assembly comprising isolator plates adapted to be placed between the metal components of a wall assembly and made of an insulating material. The isolator plates include at least one opening for receiving a fastener, said opening has an annular shoulder adapted to extend into an opening for receiving said fastener in a metal component of a wall assembly. Also disclosed herein is a thermal isolation washer and a girt for use with polymer panel construction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of and claims priority fromU.S. patent application Ser. No. 12/928,151, filed Dec. 6, 2010, whichis incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

The construction, maintenance, and habitation of buildings is the singlebiggest contributor of greenhouse gases, and heating and cooling systemsaccount for up to 50% of energy used in buildings in the United States.Reducing the energy used to heat and cool buildings is critical toenergy conservation, and energy conservation is critical to bothnational security and economic prosperity.

A variety of governmental and non-governmental organizations are causinga tightening of energy efficiency standards as they pertain tobuildings. In 1992, Congress passed the Energy Policy Act which requiredstates to have building codes that set efficiency standards that are atleast as stringent as the Federal standard. The American Society ofHeating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standard90.1 “Energy Standards for Buildings Except Low Rise ResidentialBuildings” is followed by most states who update their state codes as90.1 is updated. The 2030 Challenge, adopted by the US Conference ofMayors, AIA, USGBC, ASHRAE, and other important governmental andnon-governmental organizations, requires new buildings to reduce energyuse by 60% in 2010, 70% by 2015, 80% by 2020, 90% by 2025, and toachieve carbon neutrality by 2030. Meeting these tighter standards willrequire improvements in design and construction.

Energy efficiency is not the only demand made of construction. Thebuilding envelope, or the enclosure, must withstand occupant loads, windloads, fire, precipitation, and humidity and condensation, as well asinsulate the building. These requirements are codified through a numberof standards. In addition to ASHRAE standard 90.1-2007, National FireProtection Association (NFPA) standard 285 identifies flame propagationrequirements for exterior non-load bearing wall assemblies used innon-combustible construction. American Society for Testing and Materials(ASTM) standard E-331 dictates water barrier property requirements. ASTME-2357 dictates air barrier property requirements. Additionally,exterior-facing and interior, room-facing wall surfaces must beaesthetically appealing.

To meet these different requirements, a building envelope is constructedof a number of different materials, typically applied in layers. Thewalls of buildings are commonly constructed from frames composed ofstuds attached at their bases to a wall plate and at their tops to aceiling plate. A wall assembly is built by attaching multiple buildingcomponents to and within the frame. Non-combustible walls are commonlyconstructed with steel framing which provides the basic structure.Layers are applied to the framing to meet aesthetic and performancerequirements. These layers typically sheathing, which can be made ofexterior grade gypsum board. Gypsum board adds to the strength of thewall, and can provide fire resistance as well as serving as a base formoisture, air, or vapor layers. One or more moisture, air, or vaporresistant barriers formed of material such as asphalt impregnated paper,plastic sheeting, or building wrap is typically located outside thesheathing. Insulating layers such as mineral wool insulation or otherinsulation reduce heat transfer through the wall. External finishingcladding provides additional protection and makes the wall visuallyappealing. Drywall, or interior gypsum wall board, is often used tofinish an interior wall as well as to provide further fire protection.Fiber batting insulation installed within the cavities between studscontributes reducing heat loss. Walls may also be made of concrete,which also comprises metal support structures, the inclusion ofmoisture, air, and/or vapor barriers, and fastening systems which holdthe various components together.

The studs, or wall frame, provide the structural strength of the walland form a base to apply the various layers which function to resistwind loads, repel moisture, and maintain internal temperature. Theenvelope and the methods used to affix its constituent materials to thestuds must withstand all forces experienced by the building. Windblowing against a building exerts a positive pressure on the windwardside and suction, or negative pressure, against the leeward side.Depending on the wind, negative pressures can be exerted against othersides of the building or the roof. Internal pressures from stack effector mechanical systems also act on the building envelope. Thus, allmaterials need to be attached with fastening systems that can resist notonly the weight of the materials themselves, but the compressive andnegative forces of wind, and wind-created negative pressures. Fasteningsystems must also be able to resist deformation. The weight of a façadeor exterior cladding installed over several inches of insulation cancreate a large moment of force and shear force which act on fastenersextending through materials positioned between studs and the exteriorcladding. Ineffective fasteners can creep over time, resulting inbuilding component damage and failures. For example, if fasteningsystems do not protect the interior insulating layers against the forcesexerted by exterior layers, insulating materials can be crushed ordeformed and lose insulating properties.

For these reasons, building envelopes are conventionally constructedwith robust fastening systems such as metal Z gifts installed over theexterior sheathing, allowing insulation to be installed on the exteriorand providing a structural base for the cladding. Such fastening systemsare strong because they involve a significant amount of material, employlarge surface areas which can provide continuous support to componentssuch as panels, and thereby enable the constituent elements of thebuilding envelope to withstand the various forces they are expected toencounter. Unfortunately, cladding fastening systems also tend toundermine the effectiveness of the exterior insulation by creatingthermal bridges, commonly lowering the effective R-value of thecompleted wall assembly to less than required by the energy codes andstandards.

Heat flows from higher temperature regions to lower temperature regionsthrough conduction, convection, or radiation. Materials that conductheat well are called conductors, and materials that do not conduct heatwell are called insulators. Thermal resistance is a measure of heatflow. Under uniform conditions, it is the ratio of the temperaturedifference across an insulator and the heat flux. It is typicallyexpressed as an R-value in construction arts. Conductors have lowR-values and insulators have high R-values.

An assembly's effective R-value is calculated by area, by averagingR-values of the various components which are parallel (side by side) andadding R-values of components that are in series (layers). The effectiveR-value of an assembly will be less than the R-value of the insulationcomponent due to parallel heat flow through more conductive components.In light gauge steel-framed assemblies, heat flows through the steelstuds can mean that the R-value of the wall is less than half of theR-value of the insulation used in the wall. Designers, contractors andcode officials often mistakenly equate the insulation R value and thewall R value and do not recognize that the metal conducts heat well andsignificantly reduces the R value of the actual wall below the R valueof the insulation itself.

Any thermally conductive part of an assembly that forms a pathwaythrough insulating materials lowers the R-value of a building envelope.Studs and tracks, fasteners, structural members, and cladding supportstructures are all conductive. When conductive materials are used tofasten materials to wall frames, they contact the frames and extendthrough insulating layers, creating a path of least thermal resistancefrom the warm studs to the cold exterior and facilitating parallel heatloss through the wall. The warm building interior will warm wall studs,and that heat is easily conducted to the bracket or Z girt that is insubstantial contact with the steel stud, and those brackets and Z girtsextend through the insulation so that the heat is channeled to the coldexterior of the building. The surface area of brackets and Z girts thatprotrude through the insulation especially enables them to radiate theheat into the cold environment outside the insulating layer of thebuilding. This phenomena is also known as a “fin effect.” As a result,the wall in question will have an inadequate R-value and the problemgets worse with increasing levels of insulation. Additionally, thethermal bridges will create warm or cold spots within a wall, which canlead to condensation and resulting mold and water damage.

In response, the conventional approach in the building industry is touse a thicker layer of insulation. However, this solution does notresolve the thermal bridging problem because the cladding is stillattached to metal components which extend through the insulation. Addinginsulation around thermal bridges has no impact on the conductive natureof the thermal bridge. If enough insulation is added, the wall as awhole may eventually achieve the target R-value, but the problems causedby the creation of warm or cold spots within the wall will persist. Thelaw of diminishing returns applies. Each additional thickness ofinsulation has decreasing effectiveness. The first few inches ofinsulation deliver the most efficiency, and each additional inch yieldsless return. Eventually additional insulation does not contribute anyadded insulation value. Therefore walls with significant thermal bridgesmay never meet their intended R value.

A wall with a thermal bridge may be analogized to a bucket with a holein it. Adding insulation without breaking thermal bridges is likeincreasing the thickness of the walls of the bucket but not plugging thehole.

Metal fasteners are used despite these disadvantages because of the highstrength of metals such as steel, and the fact that metal fasteners canbe economically manufactured in a variety of different configurationsusing known methods. No other material offers this combination ofattributes in this context. What is needed are methods of using metalfasteners to fasten elements of a building envelope to studs thatinterrupt the thermal bridges created by those metal fasteners. However,any such methods must withstand the demands that occupants,environmental forces, and gravity make on building envelopes. Thestructural integrity of buildings is critical to human health andsafety. The fasteners that hold together buildings must withstand thevarious positive and negative pressures of wind, the substantial weightof the envelope components, and extraordinary events such as hurricanesand earthquakes. Fundamental technologies such as steel bracketsconnected to steel studs with steel bolts have a long, establishedhistory of withstanding these forces and keeping people safe. What isstill needed is means of interrupting the thermal bridges created bymetal fastening systems which does not impair the structural integrityof those fastening systems.

Conventionally, building envelopes include a structural layer such asgypsum board and an insulating layer such as mineral wool, both of whichare affixed to wall frames. However, Dow produces and markets polymericfoam boards which provide both structure and insulation. Dow marketsthis product under the THERMAX trademark. These polymeric foam boardsare described in US Pub. No. 2009/0320397. As Dow notes in thereferenced published patent application, however, metal fasteners mustextend through the insulating polymeric boards and attach to the metalwall frame. See paragraph 38. These metal fasteners create thermalbridges which compromise the effectiveness of the insulation. Moreover,these boards provide substantial structural strength—far more thanmineral wool insulation. Traditional methods of mounting cladding to aconventional wall such as Z-girts do not take advantage of theproperties of rigid foam boards, which are capable of withstandingconsiderable compressive force, especially spread over significantsurface area. A method of mounting cladding to foam boards such asTHERMAX in a way that does not create thermal bridges would bedesirable.

SUMMARY OF THE INVENTION

Disclosed herein is an isolator system for preventing the conduction ofthermal energy between two metal components of a wall assemblycomprising: an isolator plate for placement between a wall stud and afastening member having a surface area adapted to be placed incommunication with said wall stud, said plate comprised of an insulatingmaterial and sized to be approximately coextensive with said surfacearea of said fastening member which is in communication with said wallstud, said plate including at least one opening for receiving afastener, said opening including an annular shoulder adapted to extendinto an opening for receiving said fastener in said fastening member.

Also disclosed herein is a wall assembly comprising: a support structurecomprised of metal studs having two ends, one said end being affixed toa wall plate and the other said end being affixed to a ceiling plate;one or more fastening members comprised of metal and having a surfacearea in communication with a portion of said support structure, saidsurface area and said portion of said support structure defining aregion between said fastening member and said support structure; anisolator plate comprised of insulating material and located in andconfigured to be approximately coextensive with said region; a fastenerextending through openings in each said support structure, saidfastening member, and said isolator plate; and said opening in saidisolator plate being surrounded by an annular shoulder which extendsinto said opening in said fastening member.

Also disclosed herein is a wall assembly, comprising: a supportstructure comprised of metal studs having two ends, one said end beingaffixed to a wall plate and the other said end being affixed to aceiling plate; one or more insulating foam panels; one or more girtshaving an approximately rectangular cross section and at least threesides; one or more fasteners extending through openings in said girts,said fasteners extending through said panels and having terminal endsattached to said support structures; and an isolating washer mounted oneach said fastener, said isolating washers configured and located toprevent contact between said fastener and said girt.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a conventional wall assembly.

FIG. 2 is a perspective view of one embodiment of the isolating platedisclosed herein.

FIG. 3 is a perspective view of one embodiment of the isolating platedisclosed herein mounted on a bracket.

FIG. 4 is a perspective view of one embodiment of the isolating platedisclosed herein mounted on a bracket.

FIG. 5 is a perspective view of one embodiment of the isolating platedisclosed herein.

FIG. 6 is a perspective view of one embodiment of the isolating platedisclosed herein mounted on a bracket.

FIG. 7 is a perspective view of one embodiment of the isolating platedisclosed herein mounted on a bracket.

FIG. 8 is a perspective view of one embodiment of the isolating platedisclosed herein.

FIG. 9 is a perspective view of one embodiment of the isolating platedisclosed herein.

FIG. 10 is a perspective view of one embodiment of the isolating platedisclosed herein.

FIG. 11 is a perspective view of one embodiment of the isolating platedisclosed herein.

FIG. 12 is a perspective view of one embodiment of the isolating washerdisclosed herein.

FIG. 13 is a perspective view of one embodiment of the isolating washerdisclosed herein.

FIG. 14 is a perspective view of one embodiment of the isolating platedisclosed herein.

FIG. 15 is a perspective view of one embodiment of the isolating platedisclosed herein and a bracket upon which it may be mounted.

FIG. 16 is a perspective view of one embodiment of the isolating platedisclosed herein.

FIG. 17 is a perspective view of a fastener with one embodiment of theisolating washer disclosed herein mounted upon it.

FIG. 18 is a cross sectional view of a girt and a bracket attachedthereto with one embodiment of the thermal isolation system disclosedherein used.

FIG. 19 is a cross sectional view of a fastening member and isolatingwasher and plate.

FIG. 20 is a cross sectional view of a fastening member and isolatingwasher and plate.

FIG. 21 is a cross sectional view of a wall assembly employing oneembodiment of the invention disclosed herein.

FIG. 22 is a cross sectional view of one embodiment of the inventiondisclosed herein.

FIG. 23 is a perspective view of one embodiment of the inventiondisclosed herein.

DETAILED DESCRIPTION

As shown in FIG. 1, a wall structure is commonly formed of vertical wallstuds 8 that are spaced apart from each other and attached to a wallplate (not shown) at one end and a ceiling plate (not shown) at theother end. The studs form cavities 16 between them, and are commonlyformed from steel. They are rigidly interconnected to both the wallplate and the ceiling plate, forming a support structure 14. The supportstructure 14 has an opposing inside facing aspect 18 and an outsidefacing aspect 20, corresponding to the building interior facing aspectof the wall and the building exterior facing aspect of the wall.Adjoining walls form corners with various angles, and window openingsand door openings are commonly defined.

The elements of the building envelope are attached to the supportstructure 14. Conventionally, sheathing 22 such as plywood, orientedstrand board, or exterior grade gypsum board may be attached to theoutside facing aspect 20 of the support structure 14 to form a rigidenvelope layer. Insulation 17 such as mineral wool is attached to thestructure, as is a weather resistant barrier (not shown). Cladding (notshown) is affixed as the outermost layer of the building envelope.

Alternatively, stiff, insulating polymer foam boards 19 such as DuPontTHERMAX boards may be attached directly to the support structure 14 andthe sheathing and mineral wool insulation layers may be omitted. Anadditional weather resistant barrier may be affixed directly to thesupport structure or to the polymer boards. Cladding is affixed as theoutermost layer of the building envelope.

Conventionally, all of the layers of the building envelope must befastened securely to the support structure 14 in a way that allows themto withstand wind, gravity, and occupant loads as well as moisture andtemperature changes. Screws, brackets, and girts made of steel areconventionally used to accomplish this. Girts are typically horizontalstructural members, but they can be used in a vertical orientation aswell. They can have a variety of cross sections, including Z shapes. A Zgirt 21 is shown in FIG. 1. They can be used as stabilizing elements inthe primary structure, and they can support wall cladding or otherelements of the building envelope. In order to perform these functions,they need to be securely fastened to the steel studs 8 which make up thesupport structure 14. Typically they are bolted or screwed to the studs8. The screws that fasten girts to studs may extend through layers ofintervening material, such as sheathing or even insulation. If a girt isfastened directly to a stud, a portion of the surface area of the girtand a portion of the surface area of the stud are in direct contact. Ifmaterial such as sheathing is placed between the girt and the stud, thenthe corresponding surface area 29 of the girt 21 and the surface area 31of the stud 8 are in communication with one another, in that stress feltby the girt is transmitted to the stud via the communicating surfaceareas. Because they typically support loads exerted against the claddingby gravity and because they are subject to shear forces, negativepressures, and positive pressures, girts typically maximize surfacecontact with or communication with steel studs so that the stressexerted on the girt is spread over as much surface area as possible, andthis communication or contact between relatively large surface areasreduces the load on the bolts or screws connecting the two componentstogether.

A variety of fastening members 32 can be used to fasten elements of abuilding envelope to a support structure, including girts, brackets, andother structures. Fasteners which are used to attach fastening membersto support structures include screws, bolts, and tacks.

The fastening members 32 must support the cladding and resist loadswithout compacting, crushing, or deforming the insulation 17 which maybe placed between the fastening member 32 and the stud 8. Mineral woolinsulation is especially vulnerable to crushing, and its surface cannotbe used to support the load exerted by the cladding and associatedstructures. For that reason, when mineral wool insulation is used in awall, fastening members used to support cladding must do so in a waythat does not transfer any of the load from the cladding on to theinsulation. The fastening members must support the weight of thecladding and all environmental loads on the cladding, and must transferforce to the studs 8 rather than mineral wool insulation. The claddingmay be separated from the studs by several inches of insulation, and sothe force exerted by that cladding and borne by the brackets or girts isincreased by the lever effect.

The structure conventionally used to accomplish these tasks is shown inFIG. 1. Metal studs 8 form the support structure 14 of the wall.Sheathing 22 such as gypsum board or a similar structure is placed incontact with the studs 8. A fastening member 32 such as a Z girt 21 isheld in place proximal to the gypsum board by a bolt or screw 23 whichextends through the Z girt and the gypsum board and attaches to themetal stud 8. Cladding is attached to the distal end of the Z girt 24.The cladding creates a gap of several inches in which insulation 17 mayreside. The Z girt 21 in combination with the metal screw or bolt 23forms a thermal bridge which extends through the insulation 16 from thestud 8 to the exterior of the building 28.

This thermal bridge reduces the R value of the wall construct. Theconventional approach to this problem is to use a thicker layer ofinsulation. However, the inventor has discovered that thicker insulationdoes not resolve the problem of heat loss through thermal bridging.Instead, the inventor has discovered that the use of thermal isolatorscan have an unexpected beneficial impact on heat loss due to fastenerthermal bridges, and does not adversely impact the integrity of thefastener systems.

Disclosed herein is a system and method for interruption of thermalbridges formed by fastening systems which does not compromise thefunction or structural integrity of those fastening systems.

Thermal isolation system components are made from ceramics or polymers.Suitable polymeric materials include nylon, polyamide, polyester, PVC,polyoxymethylene, or the like, or blends thereof. Preferably they arehighly crystalline or highly cross-linked thermoplastic materials, butthermoset materials can also be used. Preferably, the thermal isolatorsystem components are molded, but they could be machined or evenextruded.

As shown in FIGS. 2-16, the thermal isolator system comprises a plate 30suitable for attachment to a metal fastening member 32 such as a bracketor girt. The plate 30 has a size and shape suitable to be approximatelycoextensive with that portion of the surface of a fastening component 32which is in contact or communication with a portion of the supportstructure or additional fastening member. The plate may cover an entireface of a fastening member but may not extend significantly beyond theface of that fastening member. The thermal isolation plate 30 fitsbetween metal components, as shown for example in FIG. 18, in order toreduce or eliminate metal to metal contact. Heat transfer between metalcomponents via conduction is minimized because contact is minimized orprevented by the insulating properties of the isolation plate.

The plate has a body which may have a variety of cross sections andshapes, as shown in FIGS. 2-16. It may be substantially flat.Alternatively, it may define an interior air space 34 for additionalinsulation value, as shown for example in FIGS. 5-7 and 9-11. The airspace 34 is defined by peripheral walls 36. Reinforcing members 38within the peripheral walls impart strength and rigidity to thestructure. One of ordinary skill in the art will appreciate that thereinforcing members can be present in a variety of differentconfigurations. The reinforcing members should define apertures 40 asdiscussed below.

The plate includes optional positioning structures such as tabs 42 orhooks 44 which may correspond to the edges of a fastening member such asa bracket or girt, as shown, for example, in FIG. 2-4, or to notches 46in the bracket or girt, as shown in FIG. 15. Tabs 42 or other suchprotrusions insert into notches 46 or grooves in brackets or girts.Hooks 44 on one or more sides of the plate correspond to the edges of abracket or girt and embrace those edges. Alternatively, a bracket orgirt could be wedged between two or more protrusions on the edges of athermal isolation plate. The positioning structures permit the thermalisolation plate to be removably attached to a bracket or girt duringconstruction. The positioning structures hold the thermal isolationplate in position as the wall assembly is constructed. Alternatively oradditionally, brackets or girts can be sold with isolation platesalready attached, either through tabs or hooks or through means such asadhesive.

Where the girt or bracket contains one or more openings 50 for receivinga fastener such as a bolt or screw, the thermal isolator plate has acorresponding aperture 40. The plate aperture 40 may have an annularprotrusion 48 which extends through the opening 50 in the girt orbracket. The annular protrusion 48 has an internal diameter which issized to receive a screw or bolt, and the annular protrusion preventsthe screw or bolt from contacting the interior surface 52 of the openingin the bracket or girt.

The thermal isolator system also can include a washer 54 also made of aceramic or a polymer. The thermal isolator washer 54 can be attached toa metal washer 56. It must be sized so as to have an outer diameterlarger than the head of the screw or bolt 23, and must have an innerdiameter that fits around the shaft of the bolt or screw 23. A thermalisolator washer may have a shoulder 58 which fits into an opening in aplate or girt that accommodates a screw or bolt 23, as shown for examplein FIG. 20.

As shown in FIG. 21, a screw or bolt 23 extends through the base 60 of agirt 62 and into a stud 8. A thermal isolating washer 54 separates thebolt 23 from the girt 62 so that there is no unbroken metal to metalthermal bridge between the stud 8 and the bracket. At the distal end ofthe girt 64, a bracket 66, which may be used to attach cladding to thestructure, is attached with an additional fastener 22. A thermalisolation plate 30 with an annular protrusion 48 which fits within theopening 40 in the brackets separates the two metal fastening members 62and 66 and prevents the screw from contacting the inner surface of theopenings in the two brackets. A thermal isolating washer 54 prevents themetal head of the screw from contacting the metal bracket 66. In thisway, there is no thermal bridge between the stud and the outside of thebuilding 28.

Acting in concert, wherever two metal components are fastened to oneanother, one or more thermal isolator washers and plates can be used toprevent metal components from contacting one another, and to preventcontact between the bolt head and a metal component, thus preventing thecreation of thermal bridges. Additional washers or plates can optionallybe used, for example between a nut and a plate. These thermal isolatorsystem components can be used whenever metal systems are fastenedtogether in building construction. Because these thermal isolationsystem components are specifically placed within the construction, theyhave a surprisingly positive effect on the R value of a wall, but do notadd significantly to the cost or labor intensivity of construction. Theyalso do not negatively affect the function of the fastener systems,girts, or brackets used in construction.

Conventionally, Z girts are used to attach insulation to buildingenvelopes. Z girts are fastened to the studs, perhaps through sheathing.Strips of insulation are installed between the Z girts so that the Zgirts boarder the insulation strips. In this way, Z girts offercontinuous support to the edges of a panel of insulation, and insulationsuch as mineral wool requires that level of support in order to avoidbeing deformed by its own weight or the weight of adjacent componentssuch as cladding. Dow has recently invented and THERMAX foam boards,which are strong enough to eliminate the need for a separate sheathingrequirement. Builders have been using conventional building techniquessuch as Z girts to attach THERMAX boards directly to support structures.However, this building method has a tremendous disadvantage, in that itcreates substantial thermal bridges between the studs and the outside ofthe building. The Z girts directly contact the studs via fasteners, andextend through the insulation layer. This structure causes a loss of upto 50% of the R-value of the wall.

The inventor has developed a new girt apparatus and building methodwhich take advantage of the structural properties and materialcharacteristics of foam wall boards such as THERMAX to create a wallconstruct with no thermal bridges.

A CI girt 68 preferably has a box shape, having a square or rectangularcross section which creates a rigid structural element, as shown inFIGS. 22 and 23. It can have three or four sides, and one side may bebroken. The girt has openings 70 in the external facing side 72 largeenough to accommodate the heads of fasteners, so that the entirefastener can be inserted through the opening 70 in the external facingside 72. The internal facing side 74 has corresponding openings 76 whichmay be threaded.

In accordance with the inventive method, insulation panels 18 such asfoam wall boards are held against the structural support 14 in a knownmanner. CI girts 68 are placed against the outward facing side of theinsulation panels 18 and aligned with the studs 8 in the supportstructure. Screws or bolts which carry thermal isolating washers 54 areinserted through the openings 70 in the external facing side of the CIgirt 68, and are passed through the insulation panel 18 and into thesteel stud 8.

The insulation panels abut one another, and can be sealed in aconventional manner. The CI girt is fastened outside of the insulationpanels. The insulation panels separate the CI girts from the studs. Theonly metal component which breaks the insulation layer is the fastenerused to fasten the CI girt to the studs. A thermal isolation washer isused to interrupt thermal bridging otherwise caused by that fastener. Inthis way, foam wall boards are used in a way that provides trulycontinuous insulation. Additionally, the CI girt's rigid shape transferswind and gravity load evenly to the surface area of the insulation,which makes it possible to add heavier cladding.

In contrast, conventional insulation panels are placed between Z girtsso that no insulation separates the Z girts from the studs and Z girtsborder the insulation panels, and substantial thermal bridges arecreated.

A fastening system for the attachment of cladding 76 can then be affixedto the CI girts using fasteners which do not extend through theinsulation panels, which permits the CI girts to both attach theinsulation panels to the studs and to attach the cladding to thebuilding envelope.

A moisture proof membrane or other envelope materials can be placedbetween the CI girts and the insulation panels, or between theinsulation panels and the studs.

Thermal modeling and analysis of wall assemblies demonstrates that theuse of the inventive CI girts and thermal isolation system provides asignificant and unexpected benefit in R value.

Morrison Hershfield, an independent third party, conducted a thermalanalysis to determine the effective R values of wall assemblies whichemployed Z girts to attach THERMAX wall boards to metal studs and wallassemblies which employed the inventive CI girts and thermal isolatorwashers to attach wall board to metal studs in a way that avoided thecreation of thermal bridges.

Cases G through F were modeled. Cases G and H employed conventionalgirts and no thermal isolators, and cases I though J employed CI girtswith thermal isolators.

TABLE 3 Assembly U-Values and Effective R-Values for modeled cases withno interior insulation Exterior Exterior Insulation Assembly InsulationNominal Nominal Assembly Assembly Thickness R-Value R-Value U-ValueEffective R Case (In) (hr · ft² · ° F./BTU) (hr · ft² · ° F./BTU) (hr ·ft² · ° F./BTU) (hr · ft² · ° F./BTU) % Effective G 1.55 10.1 13.3 0.1188.4 63% Vertical Girts (Girts spaced horizontally 16″o.c., no interiorsprayfoam) H 1.55 10.1 13.3 0.105 9.5 71% Horizontal Girts (Girts spacedvertically 24″o.c., no interior sprayfoam) I 1.55 10.1 12.8 0.080 12.598% CI System (Fasteners vertically spaced 16″o.c., no sprayfoam) J 3.0019.0 21.7 0.048 20.7 95% CI System (Fasteners vertically spaced 16″o.c.,no sprayfoam)

The results establish that the inventive systems for minimizing thermalbridges work extremely well. In cases H and G, the thermal bridgingcreated by the conventional use of girts cost the insulation 29% and 37%of its effectiveness. In contrast, when CI girts and thermal isolatorswere used, the invention maintained 95% and 98% of its effectiveness.Cases I and J had effective R values which were very close to theirnominal R values. Case I actually had a lower nominal R value than casesG or H. The conventional thinking in this field would expect that Case Iwould have a lower effective R value, however, due to the use of anembodiment of the invention disclosed and claimed herein, it had asignificantly higher effective R value.

I claim:
 1. A wall assembly, comprising: a support structure comprisinga plurality of metal studs; one or more elongate girts having at leastone side with a substantially planar elongate girt surface; one or moreinsulating foam panels positioned between at least one said girt and atleast one said metal stud, at least one of said insulating foam panelsof said one or more insulating foam panels having a substantially planarouter panel surface, a top edge, a bottom edge, a left side edge and aright side edge; said substantially planar girt surface positionedagainst said substantially planar outer panel surface and spaced apartfrom said left and right side edges of the insulating foam panel; and,at least one fastener extending through at least one opening in at leastone said girt, said fastener extending through said panels and having aterminal end attached to one said metal stud; a thermal isolatoroperably secured between the fastener and the girt, and wherein: thefastener has a head portion and a shaft portion with the shaft portionextending through the at least one said opening in said girt, the shaftportion having a cross-sectional width; the at least one said opening insaid girt is larger than the cross-sectional width of the shaft portionto define a space therebetween; said thermal isolator occupies the spacebetween the shaft portion and the girt within the at least one saidopening, thereby preventing the shaft portion from contacting the girt;and, wherein said substantially planar girt surface is positioneddirectly against said substantially planar outer panel surface withoutthe thermal isolator extending therebetween.
 2. The wall assembly ofclaim 1 further comprising an isolating washer mounted on said fastener,said isolating washer configured and located to prevent contact betweensaid fastener and said girt.
 3. The wall assembly of claim 1, whereinthe one or more insulating foam panels are substantially incompressible.4. The wall assembly of claim 1, wherein the one or more insulating foampanels are not compressed by said at least one fastener when said atleast one fastener is operably secured to the metal stud.
 5. The wallassembly of claim 2, wherein the isolating washer is made from heattransfer resistant material.
 6. The wall assembly of claim 5, whereinthe heat transfer resistant material is selected from the groupconsisting of ceramic and polymer.
 7. The wall assembly of claim 6,wherein the polymer is selected from the group consisting of nylon,polyamide, polyester, polyvinyl chloride, and polyoxymethylene.
 8. Thewall assembly of claim 5, wherein the heat transfer resistant materialis selected from the group consisting of highly crystallinethermoplastic, highly cross-linked thermoplastic and thermosetmaterials.
 9. The wall assembly of claim 2, wherein said isolatingwasher reduces thermal conductivity between said fastener and said girt.10. A wall assembly, comprising: a support structure comprising aplurality of spaced-apart and substantially parallelly aligned studs; afirst girt having at least one side with a substantially planar elongategirt surface; one or more panels positioned between at least one saidgirt and at least one said metal stud, at least one of said panel ofsaid one or more panels having a substantially planar outer panelsurface, a top edge, a bottom edge, a left side edge and a right sideedge; said substantially planar girt surface operably engaging saidsubstantially planar outer panel surface at a location spaced apart fromsaid left and right side edges of the panel; at least one fastenerextending through at least one opening-in the first girt, said fastenerextending through said panels and having a terminal end attached to onesaid stud; a first thermal isolator operably secured between saidfastener and said girt thereby preventing the fastener from directlycontacting the girt, and, the first thermal isolator spaced apart fromthe substantially planar girt surface's operable engagement of thesubstantially planar outer panel surface.
 11. The wall assembly of claim10, wherein the fastener has a head portion and a shaft portion with theshaft portion extending through the at least one said opening in saidfirst girt, the shaft portion having a cross-sectional width; the atleast one said opening in said girt is larger than the cross-sectionalwidth of the shaft portion to define a space therebetween; and, saidfirst thermal isolator occupies the space between the shaft portion andthe girt within the at least one said opening, thereby preventing theshaft portion from contacting the girt.
 12. The wall assembly of claim10, wherein the first thermal isolator is made from heat transferresistant material.
 13. The wall assembly of claim 10, wherein the heattransfer resistant material is selected from the group consisting ofceramic and polymer.
 14. The wall assembly of claim 13, wherein thepolymer is selected from the group consisting of nylon, polyamide,polyester, polyvinyl chloride, and polyoxymethylene.
 15. The wallassembly of claim 10, further including a second thermal isolatoroperably securable to the first girt surface such that it is compressedagainst the substantially planar outer panel surface of the panel whenthe fastener is operably secured to the stud.
 16. The wall assembly ofclaim 15, further including a second girt operably secured to the firstgirt and a second thermal isolator extending between said first girt andsaid second girt.